Image cloning in VMware ESX shell
VMware image clone via ESX shell and vmkfstools
The free version of the VMware vSphere Hypervisor has a reduced feature set. One of the missing features is the ability to clone or create
templates from existing vms. You can clone an image using vmkfstools within the ESX shell.
vmkfstools
OPTIONS FOR FILE SYSTEMS:
vmkfstools -C --createfs [vmfs3|vmfs5]
-b --blocksize #[mMkK]
-S --setfsname fsName
-Z --spanfs span-partition
-G --growfs grown-partition
deviceName
-P --queryfs -h --humanreadable
-T --upgradevmfs
vmfsPath
-y --reclaimBlocks vmfsPath [--reclaimBlocksUnit #blocks]
OPTIONS FOR VIRTUAL DISKS:
vmkfstools -c --createvirtualdisk #[gGmMkK]
-d --diskformat [zeroedthick
|thin
|eagerzeroedthick
]
-a --adaptertype [buslogic|lsilogic|ide
|lsisas|pvscsi]
-W --objecttype [file|vsan]
--policyFile <fileName>
-w --writezeros
-j --inflatedisk
-k --eagerzero
-K --punchzero
-U --deletevirtualdisk
-E --renamevirtualdisk srcDisk
-i --clonevirtualdisk srcDisk
-d --diskformat [zeroedthick
|thin
|eagerzeroedthick
|rdm:<device>|rdmp:<device>
|2gbsparse]
-W --object [file|vsan]
--policyFile <fileName>
-N --avoidnativeclone
-X --extendvirtualdisk #[gGmMkK]
[-d --diskformat eagerzeroedthick]
-M --migratevirtualdisk
-r --createrdm /vmfs/devices/disks/...
-q --queryrdm
-z --createrdmpassthru /vmfs/devices/disks/...
-v --verbose #
-g --geometry
-x --fix [check|repair]
-e --chainConsistent
-Q --objecttype name/value pair
--uniqueblocks childDisk
vmfsPath
OPTIONS FOR DEVICES:
-L --lock [reserve|release|lunreset|targetreset|busreset|readkeys|readresv
] /vmfs/devices/disks/...
-B --breaklock /vmfs/devices/disks/...
vmkfstools -H --help
Identify source image and destination location
Log into the ESX sever and identify the location of the source image. In
this example I will be cloning image centos-0 on datastore-1
cd vmfs/volumes/datastore-1/
/vmfs/volumes/datastore-1 # ls
centos-0
I am going to create 3 additional CentOS vm images. Create the
destination directory/s prior to running vmkfstools.
/vmfs/volumes/datastore-1 # mkdir centos-1 centos-2 centos-3
/vmfs/volumes/datastore-1 # ls
centos-0 centos-1 centos-2 centos-3
Clone the image via vmkfstools -i source destination. If not specified
the new image will be thick provisioned. The first will use the
vmkfstools command without additional options. The 2nd and 3rd will
thin provision.
Thin
These virtual disks do not reserve space on the VMFS filesystem, nor do they reserve space on the back-end storage. They only consume blocks when data is written to disk from within the VM/Guest OS. The amount of actual space consumed by the VMDK starts out small, but grows in size as the Guest OS commits more I/O to disk, up to a maximum size set at VMDK creation time. The Guest OS believes that it has the maximum disk size available to it as storage space from the start.
Thick (aka LazyZeroedThick)
These disks reserve space on the VMFS filesystem but there is an interesting caveat. Although they are called thick disks, they behave similar to thinly provisioned disks. Disk blocks are only used on the back-end (array) when they get written to inside in the VM/Guest OS. Again, the Guest OS inside this VM thinks it has this maximum size from the start.
EagerZeroedThick
These virtual disks reserve space on the VMFS filesystem and zero out the disk blocks at creation time. This disk type may take a little longer to create as it zeroes out the blocks, but its performance should be optimal from deployment time (no overhead in zeroing out disk blocks on-demand, meaning no latency incurred from the zeroing operation). However, if the array supports the VAAI Zero primitive which offloads the zero operation to the array, then the additional time to create the zeroed out VMDK should be minimal.
/vmfs/volumes/datastore-1 # vmkfstools -i centos-0/centos-0.vmdk centos-1/centos-1.vmdk
Destination disk format: VMFS zeroedthick
Cloning disk 'centos-0/centos-0.vmdk'...
Clone: 100% done.
/vmfs/volumes/datastore-1 # ls -la centos-1/
total 16778248
drwxr-xr-x 1 root root 560 Feb 3 18:27 .
drwxr-xr-t 1 root root 1820 Feb 3 18:17 ..
-rw------- 1 root root 17179869184 Feb 3 18:25 centos-1-flat.vmdk
-rw------- 1 root root 524 Feb 3 18:27 centos-1.vmdk
Clone a 2nd copy to the centos-2 directory. Specify -d thin to thin
provision this image.
/vmfs/volumes/datastore-1 # vmkfstools -i centos-0/centos-0.vmdk centos-2/centos-2.vmdk -d thin
Destination disk format: VMFS thin-provisioned
Cloning disk 'centos-0/centos-0.vmdk'...
Clone: 100% done.
/vmfs/volumes/datastore-1 # ls -la centos-2/
total 1471496
drwxr-xr-x 1 root root 560 Feb 3 18:36 .
drwxr-xr-t 1 root root 1820 Feb 3 18:17 ..
-rw------- 1 root root 17179869184 Feb 3 18:34 centos-2-flat.vmdk
-rw------- 1 root root 550 Feb 3 18:36 centos-2.vmdk
Clone a 3rd copy to the centos-3 directory
/vmfs/volumes/datastore-1 # vmkfstools -i centos-0/centos-0.vmdk centos-3/centos-3.vmdk -d thin
Destination disk format: VMFS thin-provisioned
Cloning disk 'centos-0/centos-0.vmdk'...
Clone: 100% done.
/vmfs/volumes/datastore-1 # ls -la centos-3/
total 1471496
drwxr-xr-x 1 root root 560 Feb 3 18:42 .
drwxr-xr-t 1 root root 1820 Feb 3 18:17 ..
-rw------- 1 root root 17179869184 Feb 3 18:40 centos-3-flat.vmdk
-rw------- 1 root root 550 Feb 3 18:42 centos-3.vmdk
3 new copies of the CentOS vmdk files have been created. The
vmkfstools command does not copy any of the additional files from
within the source directory. I will add some details on this at a later
time. For this example the cloned images will be added via the vSphere
Client.
Add the newly cloned images to the vSphere inventory.
Log into the vSphere Client and add a New Virtual Machine (Ctrl-N).
Step through the New Virtual Machine Wizard taking note of
Configuration and Select a Disk pages. Select Custom from the
Configuration step of the Configuration wizard.
Select Use an existing virtual disk. from the Select a Disk step of
the Configuration wizrd.
